Rotary pistons, in the nature of encased rotors with radially extending vanes which move in and out of the rotors, depending upon their location within the casing used, for example, as pumps or turbines, are known. One such device is described in U.S. Pat. No. 6,554,596 of Albert and David Patterson issued Apr. 29, 2003, in which the vane movement, in and out of the rotor, is achieved by cam surfaces within the casing which act on both inner and outer edges of the vanes.
In my co-pending U.S. patent application Ser. No. 10/680,236 entitled “Rotary Pistons”, the outward movement of the vanes is achieved by upward extensions of shoulders at the sides of each vane, which upward extensions contain pins which are seated in races continuously extending in portions of the interior wall of the casing and positioned so that as the pins move about the races, they draw their respective vanes outwardly.
Other known constructions of such vane pumps require centrifugal force, through rotation of the rotor, to force the vanes out.
Problems with such arrangements, if applied to pumps, include leakage of fluid between the vanes and consequent inability to effectively and efficiently handle fluids under high pressure. Of necessity, such devices have conventionally been of relatively small size, and, while they have been able to operate at fast speeds, they have been able to move only relatively low volumes of fluid.
Traditionally, positive displacement pumps have been of relatively complex construction and have been limited in their applications.
It is an object of the present invention to provide a positive displacement pump which is relatively economical to construct and efficient in its operation, which will be able to withstand high pressures and which will have a variety of applications.